The invention relates to sampling and monitoring systems. In particular, the invention relates to headspace sampling and monitoring systems and methods.
A sampling system is typically used to monitor manufacturing processes, in which the sampling system may include analyzing capabilities. The sampling system should obtain a representative sample with minimal operations and time. While such sampling systems have been used in industry, these sampling systems may experience analytical problems, some of which may be attributed to sampling system features and mechanics.
Manufacturing processes may produce by-products, which need monitoring, such as by sampling and analyzing. A manufacturing process may produce volatile organic compound (VOCs) by-products and volatile silicone oils at a process discharge, such as, but not limited to, an aqueous discharge. Typically, VOCs can comprise mixtures of polar and non-polar hydrocarbons. VOCs can pose analytical problems for conventional monitoring and sampling systems. Polar and non-polar hydrocarbons generally require two different and distinct processes for sampling from an aqueous discharge. Non-polar VOCs, such as, but not limited to, benzene, toluene, and aliphatic hydrocarbons including hexane, are generally sampled with a purge-and-trap method. However, polar VOCs, including but not limited to acetone, methanol, and other alcohols, are typically sampled by sparging or dynamic headspace sampling. Alternatively, polar VOCs can be sampled by direct injection gas chromatography (gc).
Various sampling and monitoring systems are known in the art. These systems include on-line systems in which sampling and monitoring is conducted in the xe2x80x9cnormalxe2x80x9d course of manufacturing processes. For example, a representative portion of some wastewater may be directed to a sampling and monitoring system for analyzing that often conducted by purge-and-trap gas chromatography (gc) systems and techniques. While an on-line system has several advantages, it is not always possible to access the wastewater in a manufacturing process. Further, the wastewater that is to be sampled and monitored may not be wastewater that is capable of being sampled on-line. For example, the wastewater may be only accessible after processing is complete, in which the wastewater is collected manually for monitoring.
The manual collection of wastewater can present several problems for sampling and monitoring. These problems include relatively high costs for collecting samples needed for the sampling and monitoring. Further, given the manual aspect of the collecting of samples for monitoring, sediment and other particulate matter may be captured in the sample. Sediments and other particulate matter are undesirable in most monitoring systems. Conduits in conventional sampling systems may be configured too narrowly and be constricted so that fouling and blockage by sediments or particulates often occurs and interrupts monitoring. Thus, filtering of influent aqueous discharge is needed. The filters in monitoring systems need to be cleaned and replaced, which is both inefficient and un-economical.
Therefore, a need exists for a headspace sampling system that can adequately and accurately monitor and sparge wastewater samples. Further, a need exists for a headspace sampling system that can provide precise and reproducible data. Furthermore, a need exists for a headspace sampling system that avoids problems with particulates and sediments in manually collected wastewater.
A headspace sampling system monitors materials in wastewater is provided in an aspect of the invention. The headspace sampling system comprises a sample receptacle that can contain a wastewater sample; a sparger chamber vapor column; a sample receptacle cover assembly that connects the sparger chamber vapor column to the sample receptacle; a sparger tube; at least one sensing device; and at least one analytic device. The sparger tube and the sample receptacle define a headspace. The sparger chamber vapor column is in communication with the sample receptacle and is closed by a sparger chamber vapor column cover at a second end that is opposed to the sample receptacle. The sparger tube extends into the sample receptacle and the wastewater sample in the sample receptacle. The sparger tube is connected to a source of inert gas at a first end opposed to the sample receptacle and comprises a dispersion device at an end opposed to the first end. The sensing device is disposed in the headspace sampling system in the headspace. The analytic device in communication with the at least one sensing device. Inert gas can flow through the sparger tube into the wastewater sample to separate materials from the wastewater, the sparged materials entering the headspace of the headspace sampling system. The sparged materials are sensed by the sensing device thus providing material signal characteristics, which can be analyzed by the analytic device to determine characteristics of the material from the material signal characteristics and provide information about the characteristics of the material.
Another aspect of the invention provides a method for monitoring materials in wastewater. The method comprising steps of providing a wastewater sample in receptacle, in which the wastewater sample is to be monitored; providing a sparger chamber vapor column; disposing the receptacle and sparger chamber vapor column in fluid cooperation so as to define a headspace in the receptacle and sparger chamber vapor column; providing a sparger tube extending into the receptacle and the wastewater sample therein, the sparger tube comprising a dispersion device to expel air into the wastewater sample; providing a flow of inert gas to the dispersion device to separate materials from the wastewater sample into the headspace; sensing the separated materials; and analyzing the separated materials to provide information about the characteristics of the material.
A further aspect of the invention sets forth a headspace sampling system for separating materials from wastewater, for monitoring the materials separated from the wastewater, analyzing the materials, and communicating results of the analyzing. The headspace sampling system comprises a sample receptacle that can contain a wastewater sample that is to be monitored; a sparger chamber vapor column; a sample receptacle cover assembly comprising a sample receptacle cover and a mounting ring, the sample receptacle cover assembly connects the sparger chamber vapor column to the sample receptacle, the sparger tube and the sample receptacle defining a headspace, the sparger chamber vapor column being in communication with the sample receptacle at a first sparger chamber vapor column end and being closed by a sparger chamber vapor column cover at a second end opposed to the sample receptacle; a sparger tube that extends into the sample receptacle and the wastewater sample in the sample receptacle, the sparger tube being connected to a source of inert gas at a first end opposed to the sample receptacle, sparger tube comprising a dispersion device at an end opposed to the first end; at least one sensing device disposed in the headspace sampling system in the headspace; at least one analytic device in communication with the at least one sensing device; and communications links that can communicate information about the characteristics of the material. The inert gas can flow through the sparger tube into the wastewater sample to separate materials from the wastewater. The materials enter the headspace of the headspace sampling system, and can be sensed by the at least one sensing device. The at least one sensing device provides material signal characteristics, which can be analyzed by the analytic device to determine characteristics of the material from the material signal characteristics and provide information about the characteristics of the material.
These and other aspects, advantages and salient features of the invention will become apparent from the following detailed description, which, when taken in conjunction with the annexed drawings, where like parts are designated by like reference characters throughout the drawings, disclose embodiments of the invention.